Semiconductor optical integrated device

Abstract

A semiconductor optical integrated device in which a forward-bias optical device and a semiconductor laser are monolithically integrated on a semiconductor substrate, includes: a passive waveguide portion that is arranged between the forward-bias optical device and the semiconductor laser; and a ground electrode that is arrange on a lower surface of the semiconductor substrate. Further, the semiconductor laser includes a mirror having a length on a side closer to the forward-bias optical device, the forward-bias optical device includes a forward-bias optical-device electrode on a side opposite to a side in contact with the semiconductor substrate, the passive waveguide portion includes a passive waveguide electrode on a side opposite to a side in contact with the semiconductor substrate, and the passive waveguide electrode is electrically connected to the ground electrode.

What is claimed is: 
     
       1. A semiconductor optical integrated device in which a semiconductor optical amplifier and a semiconductor laser are monolithically integrated on a semiconductor substrate, the semiconductor optical integrated device comprising:
 a passive waveguide portion arranged between the semiconductor optical amplifier and the semiconductor laser; and 
 a ground electrode arranged on a lower surface of the semiconductor substrate, wherein 
 the semiconductor laser is a wavelength-tunable laser and includes first and second mirrors each having length, a gain portion, and a phase adjusting portion, the second mirror being arranged on a side closer to the semiconductor optical amplifier, 
 the second mirror is a distributed bragg reflector made from semiconductor, 
 the semiconductor optical amplifier includes a semiconductor optical amplifier electrode on a side opposite to a side in contact with the semiconductor substrate, 
 the passive waveguide portion includes a passive waveguide electrode on a side opposite to a side in contact with the semiconductor substrate, 
 the passive waveguide electrode is electrically connected to the ground electrode, 
 the passive waveguide portion is arranged between the second mirror and the semiconductor optical amplifier, 
 the semiconductor laser and the semiconductor optical amplifier are optically connected via the passive waveguide portion, 
 the second mirror, the semiconductor optical amplifier, and the passive waveguide portion are faced with a common upper cladding layer on a side opposite to a side in contact with the semiconductor substrate, 
 the first mirror and the gain portion have a buried structure in which a stripe mesa structure is buried on both sides with a current blocking structure constituted of a p-type InP buried layer and a n-type InP current blocking layer, 
 the common upper cladding layer on the buried structure is a common upper cladding layer in the first mirror and the gain portion, 
 the second mirror is configured to be variable in wavelength characteristics by changing a refractive index of an optical waveguide layer of the second mirror by heating with a heater provided with the second mirror, and 
 a leakage current from the semiconductor optical amplifier flows through the passive waveguide portion. 
 
     
     
       2. The semiconductor optical integrated device according to  claim 1 , wherein
 a length of the passive waveguide electrode is shorter than a length of the passive waveguide portion. 
 
     
     
       3. The semiconductor optical integrated device according to  claim 1 , wherein
 the passive waveguide electrode is arranged in the passive waveguide portion, avoiding right above the optical waveguide layer of the passive waveguide portion. 
 
     
     
       4. The semiconductor optical integrated device according to  claim 1 , wherein
 a length of the semiconductor optical amplifier electrode is shorter than a length of an active core layer of the semiconductor optical amplifier, and the semiconductor optical amplifier electrode is not arranged on an end portion on a side closer to the passive waveguide portion of the active core layer. 
 
     
     
       5. The semiconductor optical integrated device according to  claim 1 , wherein
 the passive waveguide portion includes a trench on a side closer to the semiconductor optical amplifier relative to the passive waveguide electrode. 
 
     
     
       6. The semiconductor optical integrated device according to  claim 1 , wherein
 the first mirror is a distributed bragg reflector.